<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CodeSphere OJ - 在线编程评测平台</title>
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css">
    <style>
        :root {
            --primary: #4361ee;
            --secondary: #3f37c9;
            --accent: #4895ef;
            --light: #f8f9fa;
            --dark: #212529;
            --success: #4cc9f0;
            --danger: #f72585;
            --warning: #f8961e;
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Poppins', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            background-color: var(--light);
            color: var(--dark);
            line-height: 1.6;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }
        
        /* 导航栏 */
        nav {
            background-color: white;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
            padding: 20px 0;
            position: sticky;
            top: 0;
            z-index: 100;
        }
        
        .navbar {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .logo {
            font-size: 1.8rem;
            font-weight: 700;
            color: var(--primary);
            text-decoration: none;
            display: flex;
            align-items: center;
        }
        
        .logo i {
            margin-right: 10px;
            color: var(--accent);
        }
        
        .nav-links {
            display: flex;
            gap: 30px;
        }
        
        .nav-links a {
            color: var(--dark);
            text-decoration: none;
            font-weight: 500;
            transition: color 0.3s;
        }
        
        .nav-links a:hover {
            color: var(--primary);
        }
        
        /* 英雄区域 */
        .hero {
            padding: 80px 0;
            text-align: center;
        }
        
        .hero h1 {
            font-size: 3.5rem;
            margin-bottom: 20px;
            color: var(--dark);
            line-height: 1.2;
        }
        
        .hero p {
            font-size: 1.2rem;
            color: #666;
            max-width: 700px;
            margin: 0 auto 40px;
        }
        
        .cta-button {
            display: inline-block;
            background-color: var(--primary);
            color: white;
            padding: 15px 30px;
            border-radius: 50px;
            text-decoration: none;
            font-weight: 600;
            font-size: 1.1rem;
            transition: all 0.3s;
            box-shadow: 0 4px 15px rgba(67, 97, 238, 0.3);
        }
        
        .cta-button:hover {
            background-color: var(--secondary);
            transform: translateY(-3px);
            box-shadow: 0 6px 20px rgba(67, 97, 238, 0.4);
        }
        
        /* 特性展示 */
        .features {
            padding: 80px 0;
            background-color: white;
        }
        
        .section-title {
            text-align: center;
            margin-bottom: 60px;
        }
        
        .section-title h2 {
            font-size: 2.5rem;
            color: var(--dark);
            margin-bottom: 15px;
        }
        
        .section-title p {
            color: #666;
            max-width: 600px;
            margin: 0 auto;
        }
        
        .features-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
        }
        
        .feature-card {
            background-color: var(--light);
            border-radius: 10px;
            padding: 30px;
            text-align: center;
            transition: transform 0.3s, box-shadow 0.3s;
        }
        
        .feature-card:hover {
            transform: translateY(-10px);
            box-shadow: 0 10px 30px rgba(0,0,0,0.1);
        }
        
        .feature-icon {
            font-size: 2.5rem;
            color: var(--primary);
            margin-bottom: 20px;
        }
        
        .feature-card h3 {
            font-size: 1.5rem;
            margin-bottom: 15px;
            color: var(--dark);
        }
        
        .feature-card p {
            color: #666;
        }
        
        /* 页脚 */
        footer {
            background-color: var(--dark);
            color: white;
            padding: 50px 0 20px;
            text-align: center;
        }
        
        .footer-content {
            margin-bottom: 30px;
        }
        
        .footer-links {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 30px;
        }
        
        .footer-links a {
            color: white;
            text-decoration: none;
            transition: color 0.3s;
        }
        
        .footer-links a:hover {
            color: var(--accent);
        }
        
        .copyright {
            color: rgba(255,255,255,0.7);
            font-size: 0.9rem;
        }
    </style>
</head>
<body>
    <!-- 导航栏 -->
    <nav>
        <div class="container navbar">
            <a href="#" class="logo">
                <i class="fas fa-code"></i>
                CodeSphere
            </a>
            <div class="nav-links">
                <a href="#">首页</a>
                <a href="all_questions">题库</a>
                <a href="#">竞赛</a>
                <a href="#">讨论</a>
                <a href="#">关于</a>
            </div>
        </div>
    </nav>

    <!-- 英雄区域 -->
    <section class="hero">
        <div class="container">
            <h1>提升你的编程技能</h1>
            <p>CodeSphere OJ 是一个专业的在线编程评测平台，提供海量算法题目、实时评测系统和活跃的编程社区，帮助你成为更好的程序员。</p>
            <a href="all_questions" class="cta-button">开始刷题 <i class="fas fa-arrow-right"></i></a>
        </div>
    </section>

    <!-- 特性展示 -->
    <section class="features">
        <div class="container">
            <div class="section-title">
                <h2>为什么选择 CodeSphere?</h2>
                <p>我们提供全方位的编程学习体验，帮助你高效提升编程能力</p>
            </div>
            <div class="features-grid">
                <div class="feature-card">
                    <div class="feature-icon">
                        <i class="fas fa-bolt"></i>
                    </div>
                    <h3>实时评测</h3>
                    <p>提交代码后立即获得反馈，详细的结果分析帮助你快速定位问题</p>
                </div>
                <div class="feature-card">
                    <div class="feature-icon">
                        <i class="fas fa-database"></i>
                    </div>
                    <h3>丰富题库</h3>
                    <p>超过1000道精心设计的题目，涵盖算法、数据结构、编程语言等各个方面</p>
                </div>
                <div class="feature-card">
                    <div class="feature-icon">
                        <i class="fas fa-chart-line"></i>
                    </div>
                    <h3>学习曲线</h3>
                    <p>从入门到进阶的科学题目编排，循序渐进提升你的编程能力</p>
                </div>
                <div class="feature-card">
                    <div class="feature-icon">
                        <i class="fas fa-users"></i>
                    </div>
                    <h3>活跃社区</h3>
                    <p>与来自全球的程序员交流讨论，分享解题思路和学习经验</p>
                </div>
                <div class="feature-card">
                    <div class="feature-icon">
                        <i class="fas fa-trophy"></i>
                    </div>
                    <h3>定期竞赛</h3>
                    <p>参加我们的编程竞赛，挑战自我，赢取奖励</p>
                </div>
                <div class="feature-card">
                    <div class="feature-icon">
                        <i class="fas fa-laptop-code"></i>
                    </div>
                    <h3>在线IDE</h3>
                    <p>内置功能强大的在线编程环境，支持多种编程语言，无需本地配置</p>
                </div>
            </div>
        </div>
    </section>

    <!-- 页脚 -->
    <footer>
        <div class="container">
            <div class="footer-content">
                <a href="#" class="logo" style="color: white; margin-bottom: 20px; display: inline-block;">
                    <i class="fas fa-code"></i>
                    CodeSphere
                </a>
                <p>让编程学习变得更简单、更高效</p>
            </div>
            <div class="footer-links">
                <a href="#">首页</a>
                <a href="problems.html">题库</a>
                <a href="#">竞赛</a>
                <a href="#">讨论</a>
                <a href="#">关于我们</a>
                <a href="#">帮助中心</a>
            </div>
            <div class="copyright">
                &copy; 2023 CodeSphere OJ. All rights reserved.
            </div>
        </div>
    </footer>
</body>
</html>